[Non-invasive home ventilation in patients with severe hypercapnic chronic obstructive pulmonary disease: The SOMNOVENT' study]. / Ventilation non invasive à domicile chez des patients BPCO sévères hypercapniques (étude SOMNOVENT').

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality, especially in cases of chronic hypercapnic respiratory failure. Following a prolonged debate, the indication and benefits of noninvasive ventilation (NIV) have been recently established. Although improved ventilation and reduction in hyperinflation appear to underlie the positive effect on NIV in COPD, only a few studies have focused on specific ventilatory algorithms for improving PaCO2. METHODS: The main objective of this study is to analyze the impact of Löwenstein's ventilatory algorithms, supposed to allow a better management of hyperinflation and its consequences on alveolar ventilation and blood gas parameters. This is an interventional study in routine care, prospective, single blind, randomized with cross over. The primary endpoint will be the transcutaneous partial pressure of nocturnal carbon dioxide. Secondary endpoints will be: abnormal respiratory events occurring during nocturnal NIV; the objective quality of sleep via polysomnography; the tolerance of ventilation and the subjective quality of sleep evaluated by auto questionnaires. EXPECTED RESULTS: The results of this study will clarify whether is it necessary to explore more the impact of the ventilatory modes developed by Löwenstein, dedicated to hypercapnic COPD patients, requiring a long-term NIV.

Quantitative and qualitative evaluation of spirometry for COPD screening in general practice.

INTRODUCTION: Proper diagnosis of COPD remains a challenge. Spirometry testing in primary care may help to reduce misdiagnosis, but its reliability as a diagnostic instrument needs to be assessed. OBJECTIVES: To investigate (1) the validity of spirometry testing performed in primary care and (2) the accuracy of the diagnostic of airflow limitation obtained by these tests. METHODS: Subjects attending a COPD screening programme had screening spirometry performed either by general practitioners (GPs) or by trained nurses or technicians, who had all received two 3-hour training sessions. Subjects with airflow limitation and a subset of subjects with normal spirometry at screening were invited to undergo confirmatory spirometry performed by trained nurses in a pulmonary function laboratory. RESULTS: Of the 4610 subjects who attended the screening sessions, 96.5% had a valid screening spirometry test. A total of 392 subjects attended the confirmatory sessions. Values measured by screening spirometry were satisfactory compared with those of confirmatory spirometry (rc=0.83). Taking confirmatory spirometry as reference, the positive predictive value of screening spirometry for the diagnosis of persistent airflow limitation was 93% with a specificity of 95%. Agreement for the diagnosis of persistent airflow limitation was substantial (k=0.80). CONCLUSION: Spirometry performed in primary care by trained personnel reliably identifies persistent airflow limitation. This may encourage pulmonologists to collaborate with primary care providers with the aim of improving appropriate diagnosis of COPD.

[The new reference equations of the Global Lung function Initiative (GLI) for pulmonary function tests]. / Les nouvelles équations de référence du Global Lung Function Initiative (GLI) pour les explorations fonctionnelles respiratoires.

Until recently, the reference equations available for pulmonary function tests (PFTs) have had several weaknesses: they have often been based on relatively weak samples of normal subjects; they used mathematical models that are not very efficient in describing the evolution of PFTs over age; there were different equations for children/adolescents and for adults; the expression of the results solely as a percentage of the predicted value did not provide a good indication of the statistical significance of any difference that may exist between a measured value and its reference value. The Global Lung Initiative (GLI) aimed to establish new reference equations for PFTs that do not have these disadvantages. Based on large, representative, reference populations and allowing individualization of homogeneous ethnic groups over a wide age range, the GLI uses a statistical model that does not have any a priori hypothesis regarding the evolution of PFTs as a function of age (these models therefore make it possible to describe, in a very precise manner, the PFTs over all age ranges). For a given PFT, the equation is the same regardless of age (no discontinuity on transition to adulthood). The GLI equations are used to define a reference value, a threshold value (lower limit of the normal) and a z-score that take into account age, sex, size and, for some PFTs, ethnicity. The reference equations of the GLI were established in 2012 for spirometry, in 2017 for the TLCO and will soon be established for lung volumes. Already the representation of ethnic groups not identified by the GLI and of subjects with extreme values of age and size is being questioned.